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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 18 Abstracts search results
Document:
SP143-04
Date:
May 1, 1994
Author(s):
B. Massicotte and A. Picard
Publication:
Symposium Papers
Volume:
143
Abstract:
Describes details of an extensive monitoring program carried out during the strengthening of the Grand Mere Bridge, a cast-in-place post-tensioned segmental box girder structure built in 1977. The testing program comprised various measurements taken before, during, and after the prestressing application. Electrical strain gages, mechanical strain gages, vibrating wire gages, and thermocouples were among the measuring instruments used. A bridge testing data acquisition system in a vehicle and an autonomous data acquisition system were used, together with manual reading devices. The field measurement program was carried out during strengthening. Some instruments used allow the monitoring of the bridge over a long-term period.
DOI:
10.14359/4608
SP143
Editors: David J. Stevens and Mohsen A. Issa
SP-143 Concrete is a truly unique material, exhibiting a wide range of mechanical, physical, and chemical properties, which in turn, are affected by the type of load condition, the constituents, the local environment, the processing method, the structural application, etc. Because of this complex behavior, it is crucial that accurate and meaningful experimental methods be developed and used, in order to efficiently utilize concrete, to guarantee the public's safety, and to minimize cost. This is particularly true in the 1990s, as new and novel concretes, admixtures, and reinforcements are developed.
10.14359/14183
SP143-09
R. Y. Miao and W. H. Yang
The interface confining stress between steel tube and core concrete is an important problem in the analysis of the behavior of concrete-filled steel tubes. However, no satisfactory experimental method to measure the interface stress directly has been developed because of the peculiar geometry of concrete-filled steel tubes. In this study, the significance of measuring interface stress is discussed, and the use of hydraulic analogy, or analogous hydraulically loaded control specimens, is introduced. In this paper, the fundamental mechanism, instrumentation, and procedure of hydraulic analogy will be described in detail together with examples.
10.14359/4583
SP143-10
M. Wecharatana and A. P. Ranasinghe
The break-off test is a recently developed nondestructive test for concrete. Although many experimental investigations have been carried out on this test, no in-depth theoretical evaluation has been done. In this study, the behavior of the break-off test specimen is investigated, and the theoretical basis of the test is explored. Based on linear elastic fracture mechanics, a model to predict the strength-manometer reading relationship of the test is proposed and compared with experimental results with good correlation. It was found that the ACI recommendation on the modulus of rupture (MOR) may be very conservative for certain members. The MOR of a rectangular beam is different from that observed from a circular cross section, such as the break-off test specimen. New MOR values are suggested for small rectangular beams and members with circular cross sections.
10.14359/4584
SP143-11
A. M. Hammad and M. A. Issa
Fracture surfaces of concrete and mortar are irregular, tortuous, and stochastic in nature. To describe irregular and rough surfaces, quantitative fractographic parameters such as profile and surface roughness, fractal dimension, Fourier spectral analysis, etc., are often used. A fractal description of fracture surfaces of concrete and mortar by utilizing a new nondestructive technique, introduced by the authors, will be presented in this paper. Compact tension-fractured concrete specimens with a compressive strength of 46.8 MPa and a maximum aggregate size of 37.5 mm and a projected fracture area (ligament area) of 46,000 mm 2 (367.5 mm long by 125 mm wide), are analyzed. Through this technique, a microphotograph is taken and stored as a binary image using an image analyzer equipped with a stereo-microscope. The result is a topographical map of the fracture surface. Since the elevation of each point on the fracture surface is defined by its intensity value, the need for actual sectioning through the fracture surface, often employed, is eliminated. One-dimensional Fourier spectral analysis (1D FFT) to estimate the fractal dimension is carried out. To check the method of analysis, synthetic profiles with a known fractal dimension are generated. The results of the analysis suggest that concrete fracture surfaces are fractal for the range of scales considered, the digitized fracture surface images are found to mimic the actual fracture surfaces, their spectra follow a power lower behavior, and the technique is very promising and suitable for such materials.
10.14359/4585
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